I reckon this could simply be a way of comiling a list of approved gamertags which can be playing prior to release. That list could maybe then be used in a ban wave, along the lines of ur names not down, u were playing early, banned?
If i remember rightly last time round loadsa people were 'unbanned' shortly after being banned, leading me to think the detection method wasnt 100%. Methods are changing all the time and personally, i would like it if someway could be found to stop early leaks, i think they spoil the buzz.